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基于鎖相放大器的電渦流金屬分類系統(tǒng)設(shè)計(jì)
電子技術(shù)應(yīng)用
張炳鑫,張志杰,張澤學(xué)
中北大學(xué) 儀器科學(xué)與動(dòng)態(tài)測(cè)試教育部重點(diǎn)實(shí)驗(yàn)室
摘要: 電渦流檢測(cè)是一種通過(guò)檢測(cè)金屬導(dǎo)體感應(yīng)出的微小渦流信號(hào)來(lái)識(shí)別被測(cè)材料性質(zhì)的方法。在利用電渦流檢測(cè)技術(shù)進(jìn)行金屬分類時(shí),微弱信號(hào)甚至?xí)辉肼曅盘?hào)完全淹沒(méi),這使提取有效信號(hào)變得非常困難。針對(duì)這種實(shí)際問(wèn)題,根據(jù)相關(guān)檢測(cè)法設(shè)計(jì)了基于鎖相放大器的金屬分類系統(tǒng)。在設(shè)計(jì)中,微弱待測(cè)信號(hào)經(jīng)過(guò)低噪聲放大后與兩路正交參考信號(hào)進(jìn)行互相關(guān),再經(jīng)過(guò)低通濾波電路后被采集,對(duì)被采集的信號(hào)進(jìn)行計(jì)算即可實(shí)現(xiàn)對(duì)微弱信號(hào)的檢測(cè)。實(shí)驗(yàn)結(jié)果表明,系統(tǒng)具有較高的精度和靈敏度,能夠極大地提高信號(hào)的信噪比,實(shí)現(xiàn)對(duì)金屬材料的快速分類,分類準(zhǔn)確率可達(dá)93%。
中圖分類號(hào):TN722 文獻(xiàn)標(biāo)志碼:A DOI: 10.16157/j.issn.0258-7998.245287
中文引用格式: 張炳鑫,張志杰,張澤學(xué). 基于鎖相放大器的電渦流金屬分類系統(tǒng)設(shè)計(jì)[J]. 電子技術(shù)應(yīng)用,2024,50(12):98-104.
英文引用格式: Zhang Bingxin,Zhang Zhijie,Zhang Zexue. Design of an eddy current metal classification system based on lock-in amplifier[J]. Application of Electronic Technique,2024,50(12):98-104.
Design of an eddy current metal classification system based on lock-in amplifier
Zhang Bingxin,Zhang Zhijie,Zhang Zexue
Key Laboratory of Instrumentation Science & Dynamic Measurement Ministry of Education,North University of China
Abstract: Eddy current testing is a method of identifying the properties of a material by detecting the tiny eddy current signals induced in a metal conductor. When using eddy current testing technology for metal classification, the weak signal may be completely overwhelmed by noise, making it very difficult to extract the effective signal. To address this practical problem, a metal classification system based on a lock-in amplifier was designed according to the relevant detection method. In the design, the weak test signal is amplified with low noise and correlated with two orthogonal reference signals, then collected after low-pass filtering circuit, and the collected signal is calculated to achieve detection of the weak signal. The experimental results show that this system has high accuracy and sensitivity, greatly improving the signal-to-noise ratio, achieving rapid classification of metal materials, with a classification accuracy of up to 93%.
Key words : AD630;phase-sensitive detection;eddy current testing;lock-in amplifier;metal classification

引言

金屬資源是國(guó)民經(jīng)濟(jì)生產(chǎn)與發(fā)展的重要資源。隨著可持續(xù)發(fā)展概念的提出,廢舊金屬回收越來(lái)越受到重視[1]。廢舊金屬回收不僅能夠?qū)崿F(xiàn)資源的循環(huán)利用,還能夠緩解土壤及水資源污染問(wèn)題。金屬回收首先要進(jìn)行金屬的識(shí)別和分類,可以通過(guò)電渦流檢測(cè)技術(shù)將不同電導(dǎo)率的廢舊金屬的電磁特性進(jìn)行表征,從而實(shí)現(xiàn)分類,高效而且成本較低[2]。電渦流檢測(cè)中關(guān)鍵在于從微弱的感應(yīng)信號(hào)中提取特征信號(hào)。目前電渦流檢測(cè)主要用阻抗分析儀進(jìn)行阻抗分解[3],但是整個(gè)系統(tǒng)設(shè)計(jì)較為復(fù)雜,成本較高且不能滿足輕量化的需求。

本文提出了一種基于鎖相放大器的金屬分類系統(tǒng),信號(hào)調(diào)理部分通過(guò)鎖相放大電路實(shí)現(xiàn),可靈活應(yīng)用于電渦流測(cè)量領(lǐng)域[4]。利用互相關(guān)理論,使得待測(cè)金屬下方的電渦流傳感器產(chǎn)生的微弱待測(cè)信號(hào)放大后與同頻且相互正交的兩路參考信號(hào)在相敏檢波器中進(jìn)行互相關(guān),再通過(guò)低通濾波電路以濾除噪聲分量得到實(shí)部和虛部電壓值,對(duì)實(shí)部和虛部電壓進(jìn)行一系列計(jì)算從而將深埋在大量的非相關(guān)噪聲中的微弱信號(hào)提取出來(lái),實(shí)現(xiàn)廢舊金屬的分類。


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作者信息:

張炳鑫,張志杰,張澤學(xué)

(中北大學(xué) 儀器科學(xué)與動(dòng)態(tài)測(cè)試教育部重點(diǎn)實(shí)驗(yàn)室,山西 太原 030051)


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